Plastic valve bag and method of making same



June 25, 1963 H. J. RANG 3,095,023

PLASTIC VALVE BAG AND METHOD OF MAKING SAME Filed Dec. 15, 1960 s a 2-"fi; "9

United States Patent 3,095,023 PLASTIC VALVE BAG AND METHOD OF MAKINGSAME Hendrik J. Rang, Sittard, Netherlands, assignor to Stamicarbon N.V., Heerlen, Netherlands Filed Dec. 13, 1960, Ser. No. 75,556

Claims priority, application Netherlands Dec. 24, 1959 4 Claims. (Cl.150-9) The invention relates to a bag made of a plastic, such as highpressure polyethene, low pressure polyethene, poly vinylchloride,mixtures of low pressure polyethene and rubber, co-polymers, etc.,whether or not strengthened with fibrous material, which bag is suitablefor the transport of pulverulent or gnanular i.e. particulatesubstances, such as fertilizers or plastics, and which is provided witha valve that can be directed inwards and can be easily closed in thiscondition by the contents of the bag.

Up to now, valve bags to be used for the transport of the materialsmentioned have been made of paper.

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ward, while the contents of the bag cannot escape easily through thisair outlet.

The invention also relates to a process by which the bag according tothe invention can be produced in a simple manner. This process ischaracterized in that a valve is fixed around part of an opening of aplastic tube, followring which, this opening is closed and the valve isWelded The invention aims at providing a plastic valve bag having such astrong construction that the plastic foil of which the bag is made canbe relatively thin. The invention also provides a valve bag made ofplastic and having an outlet through which the air can easily escape,while the con tents of the bag cannot. At the same time the inventionprovides a process by which such bags can be produced in a simple way.

The plastic valve bag according to the invention is characterized inthat it consists of a plastic tube, at least one of the two openings ofwhich is not closed over its entire length, thereby leaving a fillingopening around which a valve is fixed to the outer surface of the bag.

The aforementioned closing of the openings can have been brought aboutin various ways. 'It can have been done for example by heat-sealing. ifdesired, by means of heat-impulses. Closing can also have been carriedout by high-frequency welding, providing suitable materials have beenused.

It is essential that the valve be fitted to the outer surface of thebag. It has been established that a bag the valve of which has beenfitted to the inner surface, for example by heat-sealing, has aconsiderably weaker construction.

The valve can have various shapes. Preferably, however, the bag isprovided with a valve consisting of a plastic tube that is cut open asfar as this is necessary for fixing the valve :to the outer surface ofthe bag. In this case a better closure is obtained than in the casewhere the valve consists, for example, of two separate strips ofplastic. Depending on the stiffness of the valve and the fineness of thematerial to be transported in the bag, it is sometimes advantageous tomake a few incisions over part of the length of the valve, or to use avalve the end of which has been cut into a fringe.

The valve need not be made of the same material as the bag. To saveexpenses the valve will generally be made of a thinner material, as thedemands made on the mechanical strength of the valve need not be as highas those made upon the walls of the bag.

The valve can also consist of a thermoplastic plastic applied on acarrier, such as paper, cellophane or textile.

It is advantageous to fix the valve to a corner point of the bag. As aresult, the bag can be filled by means of the machines generally usedfor filling the known paper bags. The plastic tube used as a valverequires incision at one place only.

The valve bag according to the invention is preferably constructed insuch a way that the valve is fixed at some distance from the edge of theplastic tube. As a result of this arrangement, the incision in the tubeforming the valve is not completely closed. Through this opening air canescape from the bag when the valve is directed into the bag in one pass,While measures are taken to ensure that the walls of the plastic tubeinside the valve will not fuse together, at least not over the fullwidth of the valve, while the other opening is closed before or afterthis process.

The measures adapted for preventing the walls of the plastic tube,inside the valve, from fusing together, can simply consist in puttingbetween these walls a substance that does not fuse together with thesewalls, for example paper or metal. The length of the walls which are tobe prevented from fusing together can also be simply powdered with asubstance that does not become plastic at the welding temperature, forexample, talc powder or fertilizer powder.

Preferably, the valve is made of a plastic tube which has been cut openalong a line diverging from the generatrix of the tube forming the valveto the extent necessary for fixing the valve to the outer surface of thebag. In this way, there is obtained a bag of a stronger construction.This is probably due to the fact that the edges of the oblique incisionof the tube forming the valve, are not situated directly opposite eachother after the valve has been fastened to the bag. Now, the abovewelding pass does not involve a sudden change in material thicknessequal to twice the thickness of the tube forming the valve, but twochanges equal to one thickness only.

The single figure is a plan View of the valve bag of the presentinvention.

The invention is further explained by means of the single figure of theattached drawing, in which 1 represents a plastic tube. The opening 2 ofwhich is closed by a welding seam 3. A narrower plastic tube 4, in whichan oblique incision forming the edges 5 has been made, is placed aroundthe corner 6 of the plastic tube 1. The part of the inner wall ofopening 7 of tube 1, situated inside the narrower plastic tube 4, is nowpowdered with talc. After that, the welding seam 8 is made and, as aresult thereof, the opening 7, insofar as it is not powdered with talc,is closed and, moreover the plastic tube 4 is welded to the plastic tube1.

The valve can now be inserted in the bag in any direction desired. Whenthe bag is being filled, the air can easily escape through the airoutlets 9, which are formed by those parts of the edges 5 that aresituated between the welding seam 8 and the edge of the plastic tube 1.Owing to this construction the wall thickness of fertilizer bags made ofhigh pressure polyethene foil need be only 0.25 mm. thick.

Various deviations from the above construction are possible. The weldingpass 8, for example, need not be made in one straight line, but can alsobe made along a curved line. Neither is it necessary to make the weldingscams 3 and 8 breadthwise across a bag, they can also be madelengthwise.

I claim:

1. A valve bag for particulate substances comprising, in combination: aplastic tube having one of its ends completely closed, and having itsother end partially closed, thereby leaving a filling opening for theparticulate substances, and a valve member connected to the outersurface of the tube and about said filling opening consisting of an openplastic tubular member one side of which overlaps the end of said tubeadjacent said filling opening, having a single slit at one end thereofextending in the general longitudinal direction of the valve member andinto which the end of the tube adjacent the other side of said openingextends, whereby said valve end is enabled to be mounted about thefilling opening and sealed to said tube by a continuous seam about butnot within said filling opening.

2. A valve bag according to claim 1, wherein the slit extends obliquelyto the longitudinal axis of the valve member producing a two-stagechange in thickness at the seam uniting the bag and valve, and the valvemember is connected to the tube by an attaching seam spaced from theedge of the tube and the closed end of the tSllt, thereby providing anoutlet for the air from the bag, said outlet extending from said fillingopening out between the closed end of the slit and the attaching seam.

3. A method of producing a valve bag for particulate material,comprising the following steps: placing a valve member around a cornerof one end of an open-ended plastic tube, said valve member comprisingan open plastic tubular member of smaller diameter than said open-endedplastic tube and having a slit at one end thereof, extending in thegeneral longitudinal direction of the valve member and into which thetube extends, Isaid slit being located away from the corner of the tube,app-lying a material between the two adjacent surfaces of said tubeallong the distance fnom the corner of the tube extending to the slit,welding the open end of the one end of the tube together 4 and weldingthe valve member to the outer surface of the tube in one welding pass,the material between the two adjacent surfaces of said tube preventingwelding of the tube along that distance, and completely closing theother end of said plastic tube.

4. A method according to claim 3, wherein the valve member is slit in adirection oblique to the [longitudinal axis of the valve member thusproducing a two-stage change in thickness at the seam formed by said onewelding pass when uniting the bag and valve member, said seam beingspaced from the edge of the tube and the closed end of the slit, therebyproviding an outlet for air firom the completed bag, said outletextending from the unseamed portion out between the closed end of theslit and the attaching seam.

References Cited in the file of this patent UNITED STATES PATENTS BatesFeb. 17, 1903 Bates Dec. 22, 1908 Weekis Aug. 1,1950 Wells Dec. 12, 1950Paton May 10, 1955 Chandler Dec. 29, 1959

1. A VALVE BAG FOR PARTICULATE SUBSTANCES COMPRISING, IN COMBINATION: APLASTIC TUBE HAVING ONE OF ITS ENDS COMPLETELY CLOSED, AND HAVING ITSOTHER END PARTIALLY CLOSED, THEREBY LEAVING A FILLING OPENING FOR THEPARTICULATE SUBSTANCES, AND A VALVE MEMBER CONNECTED TO THE OUTERSURFACE OF THE TUBE AND ABOUT SAID FILLING OPENING CONSISTING OF AN OPENPLASTIC TUBULAR MEMBER ONE SIDE OF WHICH OVERLAPS THE END OF SAID TUBEADJACENT SAID FILLING OPENING, HAVING A SINGLE SLIT AT ONE END THEREOFEXTENDING IN THE GENERAL LONGITUDINAL DIRECTION OF THE VALVE MEMBER ANDINTO WHICH THE END OF THE TUBE ADJACENT THE OTHER SIDE OF SAID OPENINGEXTENDS, WHEREBY SAID VALVE END IS ENABLED TO BE MOUNTED ABOUT THEFILLING OPENING AND SEALED TO SAID TUBE BY A CONTINUOUS SEAM ABOUT BUTNOT WITHIN SAID FILLING OPENING.